mSiO2 Layer Research Articles

High-Stability Hybrid Organic-Inorganic Perovskite (CH3NH3PbBr3) in SiO2 Mesopores: Nonlinear Optics and Applications for Q-Switching Laser Operation.

Hybrid organic-inorganic perovskite shows a great potential in the field of photoelectrics. Embedding methyl ammonium lead bromide (MAPbBr3) in a mesoporous silica (mSiO2) layer is an effective method for maintaining optical performance of MAPbBr3 at room temperature. In this work, we synthesized MAPbBr3 quantum dots, embedding them in the mSiO2 layer. The nonlinear optical responses of this composite thin film have been investigated by using the Z-scan technique at a wavelength of 800 nm. The results show plural nonlinear responses in different intensities, corresponding to one- and two-photon processing. Our results support that composites possess saturation intensity of ~27.29 GW/cm2 and varying nonlinear coefficients. The composite thin films show high stability under ultrafast laser irradiating. By employing the composite as a saturable absorber, a passively Q-switching laser has been achieved on a Nd:YVO4 all-solid-state laser platform to generate a laser at ~1 μm.

Effect of Alcohol Chain Length on Formation of Cetyltrimethylammonium Bromide‐templated Mesoporous Silica Layer on Gold Nanorods

This is the first study that elucidates the effect of alcohol alkyl chain length on the formation of mesoporous silica (mSiO2) layers on cetyltrimethylammonium bromide (CTAB)‐stabilized gold nanorods (CGNRs). The growth tendencies of the mSiO2 layers on the CGNRs (CGNR@mSiO2) in various alcohol solvents differed quite substantially from those observed for previously reported spherical silica particles. The formation of the mSiO2 layer was closely related to the interaction between the CTAB bilayer and alcohol.

Covalent grafting interface engineering to prepare highly efficient and stable polypropylene/mesoporous SiO2 separator for Li-ion batteries

Due to the deficiency of low melting point and poor wettability of commercial polyolefin separators, the design and development of ceramic coating separators have been received more and more attention in Li-ion batteries recently. However, it is challenging to solve the disadvantageous exfoliation issue of ceramic coating during charge/discharge cycles and needs to be addressed urgently. Herein, a covalent grafting interface engineering strategy has been proposed to prepare a highly efficient and stable polypropylene/mSiO2 separator (PP-g-mSiO2) by the nanoscale mSiO2 layer anchoring on the surface of PP separator with covalent bonding. As expected, the covalent bonding force increase the interfacial stability of PP-g-mSiO2 separator and the mSiO2 NPs facilitate more storage of electrolyte, which results in high thermal stability, high electrolyte affinity and swift lithium-ion diffusion. When used as the separator in LIBs, the Li/LiFePO4 cell with PP-g-mSiO2 separator exhibits excellent rate capability with a discharge capacity of 101 mA h/g at 5 C and remains high capacity retention of 93% after 1000 continuous charge–discharge cycles, which suggests that the PP-g-mSiO2 separator possesses a stable and covalent grafting ceramic surface and have greater affinity to electrolyte, resulting in quicker lithium-ion diffusion and excellent cycling stability. Therefore, the covalent grafting interface modification has confirmed an effective strategy to block exfoliation issues of ceramic coating and developed the high-performance ceramic separators for LIBs.

Hydrogel-Encapsulated Mesoporous Silica-Coated Gold Nanoshells for Smart Drug Delivery.

A “smart” core@shell composite nanoparticle (NP) having dual-response mechanisms (i.e., temperature and light) was synthesized, and its efficacy in the loading and release of small molecules was explored. These core@shell NPs are composed of an optically active gold nanoshell (GNS) core and a mesoporous (m-) silica layer (m-SiO2). The GNS@m-SiO2 nanoparticles are further encapsulated within a thermo-responsive poly(N-isopropylacrylamide-co-acrylic acid) hydrogel (PNIPAM-co-AA). The multi-responsive composite NPs were designed to create thermally and optically modulated drug-delivery vehicles with a m-SiO2 layer providing additional non-collapsible space for drug storage. The influence of the m-SiO2 layer on the efficacy of loading and release of methylene blue, which serves as a model for a small-molecule therapeutic drug, was evaluated. The “smart” core@shell composite NPs having a m-SiO2 layer demonstrated an improved capacity to load and release small molecules compared to the corresponding NPs with no m-SiO2 shell. Additionally, an efficient response by the composite NPs was successfully induced by the thermal energy generated from the gold nanoshell core upon exposure to near infrared (NIR) stimulation.

Gold Nanorattles with Intense Raman In Silica Nanoparticles (Nano‐IRIS) as Multimodal System for Imaging and Therapy

AbstractHybrid colloids consisting of silica coated plasmonic core‐shell metal nanoparticles have driven progress in plethora of applications and are under intense investigation in diverse fields of research. In this regard, we have designed a multifunctional nanocomposite consisting of 1,4‐benzenedithiol (BDT) tagged gold nanorattles (Au‐NRT) as core embedded within a solid silica shell with an additional mesoporous silica shell coating forming an “IRIS” like morphology, referred to as Nano‐IRIS. The nanorattle structure with a solid gold octahedron core and porous cubic gold shell serves as an excellent SERS probe due to the presence of intrinsic electromagnetic (EM) hot‐spots. The intelligent design of incorporating a solid SiO2 layer in the core‐shell Nano‐IRIS structure helped in incorporating two different imaging functionalities, namely SERS and fluorescence‐based bioimaging into a single nanoplatform, thereby imparting a multimodal imaging attribute to Nano‐IRIS. The solid SiO2 layer not only helped in keeping the Raman reporter intact in the pores of AuNRT but also maintained the distance between the gold surface and the fluorescent drug Doxorubicin (DOX) encapsulated inside the mSiO2 layer to achieve fluorescence imaging without quenching. Additionally, Nano‐IRIS also emerged as a drug delivery system demonstrating highly efficient concentration dependent chemotherapy via ROS production and oxidative DNA damage.

Lanthanide-Doped Core-Shell-Shell Nanocomposite for Dual Photodynamic Therapy and Luminescence Imaging by a Single X-ray Excitation Source.

Photodynamic therapy (PDT) could be highly selective and noninvasive, with low side effects as an adjuvant therapy for cancer treatment. Because excitation sources such as UV and visible lights for most of the photosensitizers do not penetrate deeply enough into biological tissues, PDT is useful only when the lesions are located within 10 mm below the skin. In addition, there is no prior example of theranostics capable of both PDT and imaging with a single deep-penetrating X-ray excitation source. Here we report a new theranostic scintillator nanoparticle (ScNP) composite in a core-shell-shell arrangement, that is, NaLuF4:Gd(35%),Eu(15%)@NaLuF4:Gd(40%)@NaLuF4:Gd(35%),Tb(15%), which is capable of being excited by a single X-ray radiation source to allow potentially deep tissue PDT and optical imaging with a low dark cytotoxicity and effective photocytotoxicity. With the X-ray excitation, the ScNPs can emit visible light at 543 nm (from Tb3+) to stimulate the loaded rose bengal (RB) photosensitizer and cause death of efficient MDA-MB-231 and MCF-7 cancer cells. The ScNPs can also emit light at 614 and 695 nm (from Eu3+) for luminescence imaging. The middle shell in the core-shell-shell ScNPs is unique to separate the Eu3+ in the core and the Tb3+ in the outer shell to prevent resonance quenching between them and to result in good PDT efficiency. Also, it was demonstrated that although the addition of a mesoporous SiO2 layer resulted in the transfer of 82.7% fluorescence resonance energy between Tb3+ and RB, the subsequent conversion of the energy from RB to generate 1O2 was hampered, although the loaded amount of the RB was almost twice that without the mSiO2 layer. A unique method to compare the wt % and mol % compositions calculated by using the morphological transmission electron microscope images and the inductively coupled plasma elemental analysis data of the core, core-shell, and core-shell-shell ScNPs is also introduced.

Improving CO2 separation performance by incorporating MWCNTs@mSiO2 core@shell filler in mixed matrix membranes

To improve CO2 separation performance in mixed matrix membranes (MMMs), a novel mesoporous silica‐coated on the outer surface of multi‐walled carbon nanotube (MWCNTs@mSiO2) core@shell filler was synthesized and dispersed into Pebax MH 1657 (TPE) matrix. The introduced mSiO2 layer on the outer surface of MWCNTs have a favorable effect on the dispersion and compatibility of MWCNTs@mSiO2 core@shell filler in TPE matrix. Most importantly, the pore channels of mesoporous silica and MWCNTs constructed the feasible gas transport pathways for CO2 permeation in MMMs. The MMMs presented the best CO2 separation performance when the content of MWCNTs@mSiO2 in TPE matrix was 10 wt%. The CO2 permeability and CO2/CH4 selectivity of TPE‐MWCNTs@mSiO2‐10 membrane were 379 Barrer and 39 for CO2/CH4 mixed‐gas, respectively. The CO2 permeability and CO2/N2 selectivity of TPE‐MWCNTs@mSiO2‐10 membrane were 364 Barrer and 58 for CO2/N2 mixed‐gas, respectively. POLYM. COMPOS., 39:4486–4495, 2018. © 2017 Society of Plastics Engineers

Core-interlayer-shell Fe3O4@mSiO2@lipid-PEG-methotrexate nanoparticle for multimodal imaging and multistage targeted chemo-photodynamic therapy

Multimodal imaging-guided multistage targeted synergistic combination therapy possesses many advantages including increased tumoricidal effect, reduced toxicity, and retarded drug resistance. Herein, we have elaborately developed a core-interlayer-shell structure Fe3O4@mSiO2@lipid-PEG-methotrexatenanoparticle(FMLM), in which the Fe3O4 core could be used for magnet-stimulate-response drug release, magnetic resonance imaging, and early-phase magnet targeting ability; the mSiO2 layer could encapsulate anticancer drug doxorubicin (Dox) for chemotherapy; and the protective shell of lipid-PEG and lipid-PEG-methotrexate offered later-phase specific cellular targeting ability, good water dispersibility, and loading of photosensitizer zinc phthalocyanine (ZnPc) for simultaneous near-infrared fluorescence imaging and photodynamic therapy. Both in vitro and in vivo studies indicated that the both Dox and ZnPc-loaded FMLM (Dox/ZnPc-FMLM) exhibited the enhanced tumor accumulation, increased cellular uptake, improved anticancer activity, and weaked side effects compared with Dox/ZnPc-Fe3O4@mSiO2@lipid-PEG nanoparticle (Dox/ZnPc-FML) and free drug. For the first time, magnet targeting cooperative with methotrexate macromolecular prodrug targeting is successfully exploited to develop a promising versatile theranostic nanoplatform for dual-modal fluorescence and magnetic resonance imaging-guided combined chemo-photodynamic cancer therapy.

A novel hierarchical TiO2@Pt@mSiO2 hollow nanocatalyst with enhanced thermal stability

A novel hierarchical TiO2@Pt@mSiO2 hollow nanocatalyst with enhanced thermal stability has been synthesized successfully. The formation procedure involves a facile synthesis of SiO2@TiO2@Pt nanospheres and a subsequent solvothermal process. During the hydrothermal process, original TiO2 layer was transformed into a hierarchical nanostructure and, meanwhile, etch-released silica species redeposited on the surface of the in-situ grown TiO2 nanoplatelets. In the catalytic system, the in-situ grown TiO2 nanoplatelets were buried in the redeposited mSiO2 layers and the Pt NPs dispersed uniformly between TiO2 nanoplatelets and mSiO2 layers. Importantly, the redeposited mSiO2 layer provides a physical barrier to prevent Pt NPs from sintering up to 550 °C and the hierarchical TiO2 nanostructure shows an obvious co-catalysis effect in the reduction of 4-NP. Besides, the mSiO2 layer could also control the rapid crystallization process of TiO2 nanoplatelets effectively. In the high temperature reaction of propane dehydrogenation, HHN exhibits a lower deactivation parameter, indicating the excellent thermal stability.

Novel molecular imprinted polymers over magnetic mesoporous silica microspheres for selective and efficient determination of protocatechuic acid in Syzygium aromaticum

Improving sites accessibility can increase the binding efficiency of molecular imprinted polymers (MIPs). In this work, we firstly synthesized MIPs over magnetic mesoporous silica microspheres (Fe3O4@mSiO2@MIPs) for the selective recognition of protocatechuic acid (PCA). The resulting Fe3O4@mSiO2@MIPs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT-IR), thermo-gravimetric analysis (TGA), Brunauer–Emmett–Teller (BET), and vibration sample magnetometer (VSM), and evaluated by adsorption isotherms/kinetics and competitive adsorption. The maximum adsorption capacity of PCA on Fe3O4@mSiO2@MIPs was 17.2mg/g (2.3 times that on Fe3O4@SiO2@MIPs). In addition, Fe3O4@mSiO2@MIPs showed a short equilibrium time (140min), rapid magnetic separation (5s) and high stability (retained 94.4% after six cycles). Subsequently, Fe3O4@mSiO2@MIPs were successfully applied for the selective and efficient determination of PCA (29.3μg/g) from Syzygium aromaticum. Conclusively, we combined three advantages into Fe3O4@mSiO2@MIPs, namely, Fe3O4 core for quick separation, mSiO2 layer for enough accessible sites, and surface imprinting MIPs for fast binding and excellent selectivity, to extract PCA from complex systems.

Synthesis and Characterization of Magnetic Nanocomposite Fe<sub>3</sub>O<sub>4</sub>@nSiO<sub>2</sub>@mSiO<sub>2 </sub>with Dual Shells Containing Non-Porous Silica and Mesoporous Silica Structure

Magnetic nanocomposites of Fe3O4@nSiO2@mSiO2 were synthesized by a two-step template method. Firstly, Fe3O4 magnetic core encapsulated clusters of SiO2 nanoparticles (Fe3O4@nSiO2, non-porous SiO2) was prepared by a spray drying method. Then the core-shell spheres of Fe3O4@nSiO2 were coated further with an m-SiO2 layer (mesoporous silica) by a sol-gel process using CTAB as a template. The resultant samples were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Nitrogen adsorption-desorption and Magnetic measurements. The acquired magnetic nanocomposites possess abundant mesopores, thus extends their potential application in biomedical and wastewater treatment due to their magnetic separation ability upon an external magnetic field.

A compressible mesoporous SiO2 sponge supported by a carbon nanotube network

Applications of mesoporous silica (m-SiO2) have suffered from its fragility (monolithic m-SiO2 easily collapses under compression) and limited internal molecular exchange through small channels. Previously reported hierarchical porous m-SiO2 structures containing interconnected macropores could improve adsorption properties, but they were still intrinsically fragile without sufficient mechanical strength to sustain deformation. Here, we embed a three-dimensional carbon nanotube (CNT) skeleton into m-SiO2 to fabricate bulk, robust sponges that can be compressed to large strains (60% volume reduction) repeatedly in both air and water. This is done by directly casting a uniform m-SiO2 layer with tunable thickness onto the surface of CNTs while maintaining the original network and open porous structure, resulting in a core-shell CNT@m-SiO2 hybrid sponge. By pumping fluid through the CNT@m-SiO2 sponges under cyclic compression, the adsorption rate and efficiency of dye molecules can be significantly enhanced due to the mesoporous coating on CNTs and enhanced fluid exchange throughout internal pores. The CNT@m-SiO2 sponges may be used as robust and flexible adsorption media, and chemical and biological sensors with high performance.